The Inverted Echo Sounder (IES) is an ocean bottom-moored instrument
that measures vertical acoustic travel time (
VATT
) round trip from the
sea floor to the sea surface. With an optional
Paroscientific pressure
sensor, the instrument is designated a PIES. A combined IES, data-logger,
and acoustic release with both Paroscientific pressure and
Aanderaa current
sensors is called a CPIES (see schematic below). GSO/URI currently
produces Model 6.2 IES.